Liquid crystal composition and liquid crystal display device

ABSTRACT

The subject is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or that is suitably balanced regarding at least two characteristics. The subject is to provide an AM device that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. The invention provides a liquid crystal composition having a negative dielectric anisotropy that contains a specific compound having negatively large dielectric anisotropy as the first component, and has a specific two ring compound having a low viscosity as the second component, and provides a liquid crystal display device containing the composition.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2009-243273 filed in JAPAN on Oct. 22, 2009,the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device, and an AM device containing thecomposition. More specifically, the invention relates to a liquidcrystal composition having a positive dielectric anisotropy, and adevice containing the composition and having a mode such as twistednematic, optically compensated bend, in-plane switching or polymersustained alignment.

2. Related Art

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes phase change (PC), twistednematic (TN), super twisted nematic (STN), electrically controlledbirefringence (ECB), optically compensated bend (OCB), in-planeswitching (IPS), vertical alignment (VA) and polymer sustained alignment(PSA). A classification based on a driving mode in the device includes apassive matrix (PM) and an active matrix (AM). The PM is furtherclassified into static, multiplex and so forth, and the AM is classifiedinto a thin film transistor (TFT), a metal-insulator-metal (MIM) and soforth. The TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to the production process. Aclassification based on a light source includes a reflection typeutilizing natural light, a transmission type utilizing a backlight and asemi-transmission type utilizing both natural light and a backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be further explainedbased on a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or higher and a desirable minimum temperature ofthe nematic phase is approximately −10° C. or lower. The viscosity ofthe composition relates to the response time of the device. A shortresponse time is desirable to display moving images on the device.Accordingly, a small viscosity of the composition is desirable. A smallviscosity at a low temperature is more desirable.

TABLE 1 General Characteristics of Composition and AM Device No. GeneralCharacteristics of Composition General Characteristics of AM Device 1wide temperature range of a nematic phase wide usable temperature range2 small viscosity ¹⁾ short response time 3 suitable optical anisotropylarge contrast ratio 4 positively or negatively large dielectric lowthreshold voltage and small electric anisotropy power consumption largecontrast ratio 5 large specific resistance large voltage holding ratioand large contrast ratio 6 high stability to ultraviolet light and heatlong service life ¹⁾ A liquid crystal composition can be injected into aliquid crystal cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kinds of operating modes. In a device having a TN mode, a suitablevalue is about 0.45 micrometer. In this case, a composition having alarge optical anisotropy is desirable for a device having a small cellgap. A large dielectric anisotropy of the composition contributes to alow threshold voltage, a low electric power consumption and a largecontrast ratio of the device. Accordingly, a large dielectric anisotropyis desirable. A large specific resistance of the composition contributesto a large voltage holding ratio and a large contrast ratio of thedevice. Accordingly, a composition having a large specific resistance isdesirable at room temperature and also at a high temperature in theinitial stage. A composition having a large specific resistance isdesirable at room temperature and also at a high temperature after ithas been used for a longtime. The stability of the composition toultraviolet light and heat relates to the service life of the liquidcrystal display device. In the case where the stability is high, thedevice has a long service life. These characteristics are desirable foran AM device used in a liquid crystal projector, a liquid crystaltelevision and so forth.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device having a PSAmode. Examples of the liquid crystal composition having positivedielectric anisotropy are disclosed in the following patent documentNo. 1. The compound of a first component is described in the patentdocument No. 1.

No. 1: JP H9-77692, No. 2: JP H10-114690, No. 3: JP H11-140447, No. 4:JP 2001-354967, No. 5: JP2006-37053.

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time is desirably shorter even by onemillisecond. Thus, a composition having characteristics such as a highmaximum temperature of a nematic phase, a low minimum temperature of anematic phase, a small viscosity, a large optical anisotropy, a largedielectric anisotropy, a large specific resistance, a high stability toultraviolet light and a high stability to heat is especially desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition that has a negativedielectric anisotropy and contains two components, wherein a firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1), and a second component is at least onecompound selected from the group of compounds represented by formula(2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; R³ and R⁴ are each independently alkenyl having 2 to 12carbons; ring A is independently 1,4-cyclohexylene or 1,4-phenylene; Z¹is independently a single bond, ethylene, methyleneoxy or carbonyloxy;X¹ and X² are each independently fluorine or chlorine; m is 1, 2 or 3;Z⁴ is ethylene, methyleneoxy or carbonyloxy when m is 1 and ring A is1,4-cyclohexylene; Z¹ is independently ethylene, methyleneoxy orcarbonyloxy when m is 2, two rings A are both 1,4-cyclohexylene.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and the liquid crystal display device ofthe invention may occasionally be abbreviated to “the composition” and“the device,” respectively. A liquid crystal display device is a genericterm for a liquid crystal display panel and a liquid crystal displaymodule. The “liquid crystal compound” is a generic term for a compoundhaving a liquid crystal phase such as a nematic phase and a smecticphase, and also for a compound having no liquid crystal phases but beinguseful as a component of a composition. The useful compound has asix-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, and arod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystal compounds, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) mayoccasionally be abbreviated to “the compound (1).” “The compound (1)”means one compound, or two or more compounds represented by formula (1).“Arbitrary” is used not only in cases when the position is arbitrary butalso in cases when the number is arbitrary. However, it is not used incases when the number is 0 (zero).

A higher limit of the temperature range of a nematic phase mayoccasionally be abbreviated to “the maximum temperature.” A lower limitof the temperature range of a nematic phase may occasionally beabbreviated to “the minimum temperature.” The term “specific resistanceis large” means that a composition has a large specific resistance atroom temperature and also at a temperature close to the maximumtemperature of a nematic phase in the initial stage, and that thecomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of a nematic phaseeven after it was used for a long time. The term “a voltage holdingratio is large” means that a device has a large voltage holding ratio atroom temperature and also at a temperature close to the maximumtemperature of a nematic phase in the initial stage, and that the devicehas a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of a nematic phase evenafter it has been used for along time. When characteristics such asoptical anisotropy are explained, values which are obtained according tothe measuring methods described in Examples will be used. A firstcomponent means one compound, or two or more compounds. “The ratio ofthe first component” is expressed as a percentage by weight (% byweight) of the first component based on the total weight of the liquidcrystal composition. The same rule applies to the ratio of a secondcomponent and so forth. A ratio of an additive mixed with thecomposition is expressed as a percentage by weight (% by weight) orweight parts per million (ppm) based on the total weight of the liquidcrystal composition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. The meanings of R¹ may be identical ordifferent in two arbitrary compounds of these. In one case, for example,R¹ of the compound (1) is ethyl and R¹ of the compound (4-1) is ethyl.In another case, R¹ of the compound (1) is ethyl and R¹ of the compound(4-1) is propyl. The same rule applies to the symbols Z′, ring E¹ and soforth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. Anotheradvantage of the invention is to provide a liquid crystal compositionthat is suitably balanced regarding at least two of the characteristics.A further advantage of the invention is to provide a liquid crystaldisplay device that contains the liquid crystal composition. Anadditional advantage of the invention is to provide a liquid crystalcomposition that has a suitable optical anisotropy, a large dielectricanisotropy, a high stability to ultraviolet light and so forth, and isto provide an AM device that has a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

The liquid crystal composition of the invention satisfied at least oneof characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a suitable optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light and a highstability to heat. The liquid crystal composition was suitably balancedregarding at least two of the characteristics. The liquid crystaldisplay device contained the liquid crystal composition. The liquidcrystal composition had a suitable optical anisotropy, a largedielectric anisotropy, a high stability to ultraviolet light and soforth, and the AM device had a short response time, a large voltageholding ratio, a large contrast ratio, a long service life and so forth.

The invention includes the following items.

Item 1. A liquid crystal composition that has a negative dielectricanisotropy and includes two components, wherein a first component is atleast one compound selected from the group of compounds represented byformula (1), and a second component is at least one compound selectedfrom the group of compounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; R³ and R⁴ are each independently alkenyl having 2 to 12carbons; ring A is independently 1,4-cyclohexylene or 1,4-phenylene; Z¹is independently a single bond, ethylene, methyleneoxy or carbonyloxy;X¹ and X² are each independently fluorine or chlorine; m is 1, 2 or 3;Z⁴ is ethylene, methyleneoxy or carbonyloxy when m is 1 and ring A is1,4-cyclohexylene; Z¹ is independently ethylene, methyleneoxy orcarbonyloxy when m is 2, two rings A are both 1,4-cyclohexylene.

Item 2. The liquid crystal composition according to item 1, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-1) to (1-5):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine.

Item 3. The liquid crystal composition according to item 2, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-1).

Item 4. The liquid crystal composition according to item 2, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-5): Item 5. The liquid crystalcomposition according to item 2, wherein the first component is at leastone compound selected from the group of compounds represented by formula(1-1) and formula (1-5):

Item 6. The liquid crystal composition according to any one of items 1to 5, wherein the ratio of the first component is in the range ofapproximately 5% to approximately 70% by weight, the ratio of the secondcomponent is in the range of approximately 5% to approximately 50% byweight, based on the total weight of the liquid crystal composition.

Item 7. The liquid crystal composition according to any one of items 1to 6, further including at least one compound selected from the group ofcompounds represented by formula (3) as a third component:

wherein R⁵ is independently alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to12 carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ isindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine; ring B and ring C are each independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z² isindependently a single bond, ethylene or carbonyloxy; j is 1, 2 or 3.

Item 8. The liquid crystal composition according to item 7, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-13):

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.

Item 9. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).

Item 10. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) and (3-5).

Item 11. The liquid crystal composition according to item 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) and (3-7).

Item 12. The liquid crystal composition according to item 8, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1), formula (3-5) andformula (3-7).

Item 13. The liquid crystal composition according to any one of items 7to 12, wherein the ratio of the third component is in the range ofapproximately 10% to approximately 70% by weight based on the totalweight of the liquid crystal composition.

Item 14. The liquid crystal composition according to any one of items 1to 13, wherein the fourth component is at least one compound selectedfrom the group of compounds represented by formula (4-1) to formula(4-2):

wherein, R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring D is independently tetrahydropyran-2,5-diyl,1,4-cyclohexylene or 1,4-phenylene, and at least one ring D istetrahydropyran-2,5-diyl; ring E and F are each independently1,4-cyclohexylene or 1,4-phenylene; Z² and Z³ are each independently asingle bond, ethylene, methyleneoxy, or carbonyloxy; k is 1, 2 or 3; pand q are each independently 0, 1, 2 or 3, and the sum of p and q is 3or less.

Item 15. The liquid crystal composition according to item 14, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-1) to formula (4-1-7), and theformula (4-2-1) to (4-2-4).

wherein, R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, oralkenyl having 2 to 12 carbons in which arbitrary hydrogen is replacedby fluorine; ring E¹, E², F² and F¹ are each independently1,4-cyclohexylene or 1,4-phenylene; and Z² and Z³ are each independentlya single bond, ethylene, methyleneoxy, or carbonyloxy.

Item 16. The liquid crystal composition according to item 15, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-5).

Item 17. The liquid crystal composition according to item 15, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-1) and formula (4-1-5).

Item 18. The liquid crystal composition according to item 15, whereinthe fourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-5) and formula (4-2-3).

Item 19. The liquid crystal composition according to any one of items 14to 18, wherein the ratio of the fourth component is in the range ofapproximately 5% to approximately 40% by weight, based on the totalweight of the liquid crystal composition.

Item 20. The liquid crystal composition according to any one of items 1to 19, wherein the maximum temperature of the nematic phase isapproximately 70° C. or higher, the optical anisotropy (25° C.) at awavelength of 589 nm is approximately 0.08 or more, and the dielectricanisotropy (25° C.) at a frequency of 1 kHz is approximately −2 or less.

Item 21. A liquid crystal display device containing the liquid crystalcomposition according to any one of items 1 to 20.

Item 22. The liquid crystal display device according to item 21, whereinan operating mode of the liquid crystal display device is a VA mode, anIPS mode or a PSA mode, and a driving mode of the liquid crystal displaydevice is an active matrix mode.

The invention further includes the following items: (1) the compositiondescribed above that further includes an optically active compound; (2)the composition described above that further includes an additive suchas an antioxidant, an ultraviolet light absorbent, an antifoaming agent,a polymerizable compound and/or a polymerization initiator; (3) an AMdevice that contains the composition described above; (4) a devicehaving a mode of TN, ECB, OCB, IPS, VA or PSA and containing thecomposition described above; (5) a device having a transmission type andcontaining the composition described above; (6) use of the compositiondescribed above as a composition having a nematic phase; and (7) use ofthe composition described above as an optically active composition byadding an optically active compound to the composition.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of the compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, examples of the component compounds will bedescribed. Sixth, additives that may be mixed with the composition willbe explained. Seventh, methods for synthesizing the component compoundswill be explained. Last, use of the composition will be explained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. The composition A may furtherinclude any other liquid crystal compound, an additive and an impurity.“Any other liquid crystal compound” is different from the compound (1),the compound (2), the compound (3), the compound (4-1) and the compound(4-2). Such a compound is mixed with the composition for the purpose offurther adjusting characteristics of the composition. Of any otherliquid crystal compound, a smaller amount of a cyano compound is moredesirable in view of its stability to heat or ultraviolet light. Amoredesirable ratio of the cyano compound is 0% by weight. The additiveincludes an optically active compound, an antioxidant, an ultravioletlight absorbent, a coloring matter, an antifoaming agent, apolymerizable compound and a polymerization initiator. The impurity is acompound and so forth which contaminate the component compounds in asynthesis or other processes. Even in the case where the compound isliquid crystalline, it is classified as an impurity herein.

The composition B is essentially consisting of compounds selected fromthe group of the compound (1), the compound (2), the compound (3), thecompound (4-1) and the compound (4-2). The term “essentially” means thatthe composition may include an additive and an impurity, but does notinclude any liquid crystal compound other than these compounds. Thecomposition B has a smaller number of components than the composition A.The composition B is preferable to the composition A in view of costreduction. The composition A is preferable to the composition B in viewof the fact that physical properties can be further adjusted by addingany other liquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2 onthe basis of the effects of the invention. In Table 2, the symbol Lstands for “large” or “high”, the symbol M stands for “medium”, and thesymbol S stands for “small” or “low.” The symbols L, M and S areclassified on the basis of a qualitative comparison among the componentcompounds, and 0 (zero) means that “a value is nearly zero.”

TABLE 2 Characteristics of compounds Compound (4-1) Compound CompoundCompound Compound (1) (2) (3) (4-2) Maximum S-M S-M S-L S-M TemperatureViscosity M-L M S-M M-L Optical S-M M-L M-L M-L Anisotropy DielectricL¹⁾ L¹⁾ 0 L¹⁾ Anisotropy Specific L L L L Resistance ¹⁾Value ofdielectric anisotropy is negative and the symbol expresses the size ofits absolute value.

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) increases the absolute value of dielectricanisotropy. The compound (2) decreases the viscosity. The compound (3)increases the maximum temperature or decreases the minimum temperature.The compounds (4-1) and (4-2) increase the absolute value of dielectricanisotropy, and decrease the minimum temperature.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. The combination of the components in the composition is thefirst and second component, the first, second and third components, thefirst, second, and fourth components, and the first, second, third andfourth components. The desirable combination of the components in thecomposition is the first, second and third, components, and the first,second, third and fourth components.

A desirable ratio of the first component is approximately 5% by weightor more for increasing the absolute value of dielectric anisotropy, andis 70% by weight or less for decreasing the minimum temperature. A moredesirable ratio is in the range of approximately 10% to approximately65% by weight. An especially desirable ratio is in the range ofapproximately 15% to approximately 60% by weight.

A desirable ratio of the second component is approximately 5% by weightor more for decreasing the viscosity, and is approximately 50% by weightor less for increasing the absolute value of dielectric anisotropy.Amore desirable ratio is in the range of approximately 5% toapproximately 45% by weight. An especially desirable ratio is in therange of approximately 10% to approximately 40% by weight.

A desirable ratio of the third component is approximately 10% by weightor more for increasing the maximum temperature or decreasing the minimumtemperature, and is approximately 70% by weight or less for increasingthe absolute value of dielectric anisotropy. A more desirable ratio isin the range of approximately 15% to approximately 65% by weight. Anespecially desirable ratio is in the range of approximately 20% toapproximately 60% by weight.

A desirable ratio of the fourth component is 5% by weight or more forincreasing the dielectric anisotropy, and is approximately 40% by weightor less for decreasing the viscosity. A more desirable ratio is in therange of approximately 5% to approximately 35% by weight. An especiallydesirable ratio is in the range of approximately 10% to approximately30% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹, R² and R⁵ are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,or alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine. Desirable R¹ or R² are alkyl having 1 to 12carbons for increasing the stability to ultraviolet light or heat, or isalkoxy having 1 to 12 carbons for increasing the absolute value ofdielectric anisotropy. Desirable R⁵ is alkyl having 1 to 12 carbons forincreasing the stability to ultraviolet light or heat, or alkenyl having2 to 12 carbons for decreasing the minimum temperature. R³ and R⁴ areeach independently alkenyl having 1 to 12 carbons. R⁶ is alkyl having 1to 12, alkoxy having 1 to 12 carbons, or alkenyl having 2 to 12 carbonsin which arbitrary hydrogen is replaced by fluorine. Desirable R⁶ isalkyl having 1 to 12 carbons for increasing the stability to ultravioletlight or heat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. A more desirable alkyl is ethyl, propyl, butyl, pentyl orheptyl for decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. Amore desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. A moredesirable alkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl fordecreasing the viscosity. A desirable configuration of —CH═CH— in thealkenyl depends on the position of the double bond. Trans is preferablein the alkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl and 3-hexenyl for decreasing the viscosity. C is preferablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thealkenyl, straight-chain alkenyl is preferable to branched-chain alkenyl.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The ring A is independently 1,4-cyclohexylene or 1,4-phenylene, thearbitrary two rings A may be identical or different when m is 2 or 3.Desirable A is 1,4-phenylene for increasing the optical anisotropy. Thering B and C are each independently is 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or2,5-difluoro-1,4-phenylene, arbitrary two rings B may be identical ordifferent when j is 2 or 3. Desirable ring B or ring C is4-cyclohexylene for decreasing the viscosity. The ring D istetrahydropyran-2,5-diyl, 1,4-cyclohexylene or 1,4-phenylene, and thering D is tetrahydropyran-2,5-diyl when k is 1, and arbitrary two D maybe identical or different when k is 2 or 3, and at least one ring D istetrahydropyran-2,5-diyl. Desirable ring D is 1,4-cyclohexylene fordecreasing the optical anisotropy. Tetrahydropyran-2,5-diyl is

and preferably is

The ring E, E¹, E², F, F² and F² are each independently1,4-cyclohexylene or 1,4-phenylene, the arbitrary two ring E may beidentical or different when p is 2 or 3, and the arbitrary two ring Fmay be identical or different when q is 2 or 3. Desirable E, E¹, E², F,F² or F² is 1,4-cyclohexylene for decreasing the optical anisotropy.With regard to the configuration of 1,4-cyclohexylene in thesecompounds, trans is preferable to cis for increasing the maximumtemperature.

Z¹ and Z³ are each independently a single bond, ethylene, methyleneoxyor carbonyloxy. The arbitrary two Z² may be identical or different whenm, k or p is 2 or 3. The arbitrary two Z³ may be identical or differentwhen q is 2 or 3. Desirable Z¹ or Z³ is a single bond for decreasing theviscosity, and is methyleneoxy for increasing the absolute value ofdielectric anisotropy. Z² is each independently a single bond, ethylene,or carbonyloxy, and the arbitrary two Z² may be identical or differentwhen j is 2 or 3. Desirable Z² is a single bond for decreasing theviscosity.

X² and X² are each independently fluorine or chlorine. Desirable X¹ orX² is fluorine for decreasing the viscosity.

m, j and k are each independently 1, 2 or 3. Desirable m is 1 fordecreasing the minimum temperature. Desirable j is 1 for decreasing theminimum temperature. Desirable k is 2 for decreasing the minimumtemperature. P and q are each independently 0, 1, 2 or 3, and the sum ofp and q is 3 or less. Desirable p is 2 for increasing the maximumtemperature. Desirable q is 0 for decreasing the minimum temperature.

Z¹ is ethylene, methyleneoxy, carbonyloxy when m is 1, and the ring A is1,4-cyclohexylene. Z¹ is ethylene, methyleneoxy, carbonyloxy when m is2, and the two rings A are both 1,4-cyclohexylene.

The compound in which Z¹ is ethylene can improve the compatibility morethan the compound in which Z¹ is a single bond. The compound in which Z¹is methyleneoxy can increase the absolute value of dielectricanisotropy, and the compound in which Z¹ is ethylene can increase themaximum temperature. From the above view point, it is preferable thatthe compounds are used as the first composition so as to increase theratio of the second composition and to decrease the viscosity of thecomposition.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R⁷ is independently straight-chainalkyl having 1 to 12 carbons, or straight-chain alkoxy having 1 to 12carbons. R⁸ is straight-chain alkyl having 1 to 12 carbons, orstraight-chain alkenyl having 2 to 12 carbons. R⁹ and R¹⁰ are eachindependently straight-chain alkenyl having 2 to 12 carbons.

Desirable compound (1) are the compounds (1-1-1) to (1-5-1). Moredesirable compound (1) are the compounds (1-1-1), (1-3-1) and (1-5-1).Especially desirable compound (1) are the compounds (1-1-1), and(1-5-1). Desirable compound (2) is the compound (2-1). Desirablecompound (3) are the compounds (3-1-1) to (3-13-1). More desirablecompound (3) are the compounds (3-1-1), (3-3-1), (3-5-1), (3-7-1)(3-8-1), (3-9-1) and (3-13-1). Especially desirable compound (3) are thecompounds (3-1-1), (3-5-1) and (3-7-1). Desirable compound (4-1) are thecompounds (4-1-1-1) to (4-1-7-1). More desirable compound (4-1) are thecompounds (4-1-1-1), (4-1-3-1) (4-1-5-1) and (4-1-6-1). Especiallydesirable compound (4-1) are the compounds (4-1-1-1) and (4-1-5-1).Desirable compound (4-2) are the compounds (4-2-1-1), (4-2-1-2),(4-2-2-1), (4-2-3-1) to (4-2-3-5), the compound (4-2-4-1) and (4-2-4-2).More desirable compound (4-2) are the compounds (4-2-1-2), (4-2-3-1),(4-2-3-3) and (4-2-4-1). Especially desirable compound (4-2) are thecompounds (4-2-1-2) and (4-2-3-3).

Sixth, additives which may be mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of the optically active compound includethe compound (5-1) to the compound (5-4) below. A desirable ratio of theoptically active compound is approximately 5% by weight or less, and amore desirable ratio is in the range of approximately 0.01% toapproximately 2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance caused by heating under air, or tomaintain a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of a nematic phase evenafter the device was used for a long time.

Desirable examples of the antioxidant include the compound (6) where nis an integer of from 1 to 9. In the compound (6), desirable n is 1, 3,5, 7 or 9. More desirable n is 1 or 7. The compound (6) where n is 1 iseffective in preventing a decrease of the specific resistance caused byheating under air because it has a large volatility. The compound (6)where n is 7 is effective in maintaining a large voltage holding ratioat room temperature and also at a temperature close to the maximumtemperature of a nematic phase even after the device was used for a longtime, because it has a small volatility. A desirable ratio of theantioxidant is approximately 50 ppm or more for achieving its effect andis approximately 600 ppm or less for avoiding a decrease of the maximumtemperature or avoiding an increase of the minimum temperature. A moredesirable ratio is in the range of approximately 100 ppm toapproximately 300 ppm.

Desirable examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorbentor the light stabilizer is approximately 50 ppm or more for achievingits effect and is approximately 10,000 ppm or less for avoiding adecrease of the maximum temperature or avoiding an increase of theminimum temperature. A more desirable ratio is in the range ofapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range ofapproximately 0.01% to approximately 10% by weight. An antifoaming agentsuch as dimethyl silicone oil or methyl phenyl silicone oil is mixedwith the composition for preventing foam formation. A desirable ratio ofthe antifoaming agent is approximately 1 ppm or more for achieving itseffect and is approximately 1,000 ppm or less for avoiding a poordisplay. A more desirable ratio is in the range of approximately 1 ppmto approximately 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a polymer sustained alignment (PSA) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound isapproximately 0.05% by weight or more for achieving its effect and isapproximately 10% by weight or less for avoiding a poor display. Amoredesirable ratio is in the range of approximately 0.1% to approximately2% by weight. The polymerizable compound is preferably polymerized onirradiation with ultraviolet light or the like in the presence of asuitable initiator such as a photopolymerization initiator. Suitableconditions for polymerization, suitable types of the initiator andsuitable amounts thereof are known to a person skilled in the art andare described in the literature. For example, Irgacure 651 (registeredtrademark), Irgacure 184 (registered trademark) or Darocure 1173(registered trademark) (Ciba Japan K. K.), each of which is aphotopolymerization initiator, is suitable for radical polymerization. Adesirable ratio of the photopolymerization initiator is preferably inthe range of approximately 0.1% to approximately 5% by weight, and mostpreferably in the range of approximately 1% to approximately 3% byweight based on the weight of the polymerizable compound.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be synthesized by known methods. Thesynthetic methods will be exemplified as follows. The compound (1-1-1)is synthesized by the method described in JP H2-503441 A. The compound(2-1-1) is synthesized by the method described in JP H9-77692 A. Thecompounds (3-1-1) and (3-5-1) are synthesized by the method described inJP S59-176221 A. The compound (4-1-5-1) is synthesized by the methoddescribed in JP 2000-008040 A. The compound (4-2-2-1) is synthesized bythe method described in JP 2005-35986A. An antioxidant is commerciallyavailable. The compound of formula (6) where n is 1 is available fromSigma-Aldrich Corporation. The compound (6) where n is 7 and so forthare synthesized according to the method described in U.S. Pat. No.3,660,505.

Compounds whose synthetic methods are not described above can besynthesized according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press) and NewExperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanesetitle) (Maruzen Co., Ltd.). The composition is prepared according toknown methods using the compounds thus obtained. For example, thecomponent compounds are mixed and dissolved in each other by heating.

Last, use of the composition will be explained. The composition mainlyhas a minimum temperature of approximately −10° C. or lower, a maximumtemperature of approximately 70° C. or higher, and an optical anisotropyin the range of approximately 0.06 to approximately 0.18. The devicecontaining the composition has a large voltage holding ratio. Thecomposition is suitable for an AM device. The composition is suitableespecially for an AM device having a transmission type. The compositionhaving an optical anisotropy in the range of approximately 0.05 toapproximately 0.25, and further in the range of approximately 0.04 toapproximately 0.30 may be prepared by regulating ratios of the componentcompounds or by mixing with any other liquid crystal compound. Thecomposition can be used as a composition having a nematic phase and asan optically active composition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Itis especially desirable to use the composition for the AM device havingthe TN, OCB or IPS mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device having the transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

A composition and a compound were a subject for measurement in order toevaluate the characteristics of the composition and the compound thatwas included in the composition. When the subject for measurement was acomposition, the composition itself was measured as a sample, and thevalue obtained was described here. When the subject for measurement wasa compound, a sample for measurement was prepared by mixing the compound(15% by weight) with mother liquid crystals (85% by weight).Characteristic values of the compound were calculated from valuesobtained by measurement, according to a method of extrapolation. Thatis: (extrapolated value)=[(measured value of a sample formeasurement)−0.85×(measured value of mother liquid crystals)]/0.15. Whena smectic phase (or crystals) separated out at this ratio at 25° C., theratio of the compound to the mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight) and (1% by weight/99% by weight). Values of the maximumtemperature, the optical anisotropy, the viscosity and the dielectricanisotropy with regard to the compound were obtained by theextrapolation.

The components of the mother liquid crystals were as follows. The ratioof each component is expressed as a percentage by weight.

17.2%

27.6%

20.7%

20.7%

13.8%

Characteristics were measured according to the following methods. Mostmethods are described in the Standards of Electronic IndustriesAssociation of Japan, EIAJ-ED-2521 A or those with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Temperaturewas measured when part of the sample began to change from a nematicphase to an isotropic liquid. A higher limit of the temperature range ofa nematic phase may occasionally be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample remained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as ≦−20° C. Alower limit of the temperature range of a nematic phase may occasionallybe abbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, on irradiation with light at awavelength of 589 nanometers. The surface of the main prism was rubbedin one direction, and then a sample was dropped on the main prism. Arefractive index (n∥) was measured when the direction of polarized lightwas parallel to that of the rubbing. A refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thatof the rubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at ° C.): A sample was poured into aTN device having the distance between two glass plates (cell gap) of 9micrometers and the twist angle of 80 degrees. Sine waves (10 V, 1 kHz)were applied onto the device, and a dielectric constant (∈∥) in a majoraxis direction of liquid crystal molecules was measured after 2 seconds.Sine waves (0.5V, 1 kHz) were applied onto the device and a dielectricconstant (∈⊥) in a minor axis direction of liquid crystal molecules wasmeasured after 2 seconds. A value of the dielectric anisotropy wascalculated from the equation: Δ∈=∈∥−∈⊥.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a TN device having a normally white mode, in which thedistance between two glass substrates (cell gap) was about 4.45/Δn(micrometers) and the twist angle was 80 degrees. Voltage to be appliedonto the device (32 Hz, rectangular waves) was stepwise increased in0.02 V increments from 0 V up to 10 V. During the increase, the devicewas irradiated with light in the perpendicular direction, and the amountof light passing through the device was measured. Avoltage-transmittance curve was prepared, in which the maximum amount oflight corresponded to 100% transmittance and the minimum amount of lightcorresponded to 0% transmittance. The threshold voltage was voltage at90% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweentwo glass substrates (cell gap) was 5 micrometers. A sample was pouredinto the device, and then the device was sealed with an adhesive curableon irradiation with ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and the area A between a voltage curve and a horizontal axis in a unitcycle was obtained. The area B was an area without the decrease. Thevoltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweentwo glass substrates (cell gap) was 5 micrometers. A sample was pouredinto the device, and then the device was sealed with an adhesive curableon irradiation with ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeterand the area A between a voltage curve and a horizontal axis in a unitcycle was obtained. The area B was an area without the decrease. Thevoltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiation of a sample with ultraviolet light,evaluating the stability to ultraviolet light. A composition having alarge VHR-3 has a high stability to ultraviolet light. A TN device usedfor measurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into the device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. The value of VHR-3 is preferably 90% or more, and morepreferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the voltage holding ratio was measured,evaluating the stability to heat. A composition having a large VHR-4 hasa high stability to heat. In the measurement of VHR-4, a decreasingvoltage was measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a TN device having anormally white mode, in which the cell gap between two glass substrateswas 5.0 micrometers, and the twist angle was 80 degrees. Rectangularwaves (60 Hz, 10 V, 0.5 second) were applied to the device. The devicewas simultaneously irradiated with light in the perpendicular direction,and the amount of light passing through the device was measured. Themaximum amount of light corresponded to 100% transmittance, and theminimum amount of light corresponded to 0% transmittance. Rise time (τr;millisecond) was the time required for a change from 90% to 10%transmittance. Fall time (Σf; millisecond) was the time required for achange from 10% to 90% transmittance. The response time was the sum ofthe rise time and the fall time thus obtained.

Specific resistance (ρ; measured at 25° C.; Ω·cm): A sample of 1.0milliliter was poured into a vessel equipped with electrodes. DC voltage(10V) was applied to the vessel, and the DC current was measured after10 seconds. The specific resistance was calculated according to thefollowing equation. (specific resistance)=[(voltage)×(electric capacityof vessel)]/[(DC current)×(dielectric constant in a vacuum)].

Gas chromatographic analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The evaporator and the detector (FID)were set to 280° C. and 300° C., respectively. A capillary column DB-1(length 30 meters, bore 0.32 millimeter, film thickness 0.25 micrometer,dimethylpolysiloxane as the stationary phase, non-polar) made by AgilentTechnologies, Inc. was used for the separation of component compounds.After the column had been kept at 200° C. for 2 minutes, it was furtherheated to 280° C. at the rate of 5° C. per minute. A sample wasdissolved in acetone (0.1% by weight), and 1 microliter of the solutionwas injected into the evaporator. A recorder used was a Model C-R5AChromatopac Integrator made by Shimadzu Corporation or its equivalent. Agas chromatogram obtained showed the retention time of peaks and thepeak areas corresponding to the component compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (50 meters,bore 0.25 millimeter, film thickness 0.25 micrometer) made by ShimadzuCorporation may also be used for the purpose of avoiding an overlap ofpeaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (in moles) of theliquid crystal compounds. When the capillary columns described above areused, the correction coefficient of respective liquid crystal compoundsmay be regarded as one. Accordingly, the ratio (% by weight) of theliquid crystal compound can be calculated from the ratio of peak areas.

The invention will be explained in detail byway of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed as symbolsaccording to the definition in the following Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto the symbolized compound in Example corresponds to a compound number.The symbol (-) means any other liquid crystal compound. Ratios(percentage) of liquid crystal compounds mean percentages by weight (%by weight) based on the total weight of the liquid crystal composition.The liquid crystal composition further includes an impurity. Last,characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols. R—(A₁)—Z₁ . . .—Z_(n)—(A_(n))—R′ Symbol 1) Left Terminal Group R— C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO- C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-C_(n)H_(2n+1)—CH═CH— nV- CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF- CF₂═CH—C_(n)H_(2n)—VFFn- 4) Right Termial Group —R′ —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) -On—CH═CH₂ -V —CH═CH—C_(n)H_(2n+1) -Vn —C_(n)H₂n—CH═CH₂ -nV —CH═CF₂ -VFF—COOCH₃ -EMe 3) Bonding group —Zn— —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T—CF₂O— X —CH₂O— 10 4) Ring Structure —An—

H

Dh

dh

B

B(F)

B(2F)

B(2F,5F)

B(2F,3F)

B(2F,3F,6Me)

B(2F,3Cl)

C ro (7F,8F) 5) Example of Description

Comparative Example 1

Example 4 was selected from compositions disclosed in JP H11-140447 A.The basis for the selection was that the composition containing thecompound (2-1) has the smallest γ1. The composition was prepared andmeasured according to the above method, because the response time wasnot described. The components and characteristics thereof were asfollows.

V-HH-V1 (2-1) 24% 3-HB(2F,3F)-O2 (—) 12% 5-HB(2F,3F)-O2 (—) 12%3-HHB(2F,3F)-O2 (—) 14% 5-HHB(2F,3F)-O2 (—) 13% 3-HHB(2F,3F)-1 (—) 13%5-HHB(2F,3F)-1 (—) 12% NI = 88.5° C.; Δn = 0.090; Δε = −4.0; τ = 12.4ms.

Comparative Example 2

Example 18 was selected from compositions disclosed in JP 2001-354967 A.The basis for the selection was that the composition containing thecompound (1-5-1), (3-1-1), (3-6-1) has the smallest γ1. The compositionwas prepared and measured according to the above method, because theresponse time was not described. The components and characteristicsthereof were as follows.

3-HB(2F,3F)-O4 (—)  8% 5-HB(2F,3F)-O2 (—) 10% 5-HB(2F,3F)-O4 (—) 14%3-HBB(2F,3F)-O2 (1-5-1) 12% 5-HXB(2F,3F)-1 (—)  5% 3-HXB(2F,3F)-O4 (—) 5% 3-HBB(2F,3F)-O4 (1-5-1) 12% 3-HBB-2 (3-6-1)  9% 3-HH-V1 (3-1-1) 10%3-HH-4 (3-1-1)  5% 5-HH-V (3-1-1) 10% NI = 70.0° C.; Δn = 0.102; Δε =−3.3; Vth = 2.14 V; τ = 12.3 ms.

Comparative Example 3

Example 1 was selected from compositions disclosed in JP 2006-37053 A.The basis for the selection was that the composition containing thecompound (1-1-1), (1-4-1), (3-1-1), (3-2-1) and (4-2-1-2) has thesmallest bulk viscosity. The composition was prepared and measuredaccording to the above method, because the response time was notdescribed. The components and characteristics thereof were as follows.

2-HH1OB(2F,3F)-O2 (1-4-1) 10% 3-HH1OB(2F,3F)-O2 (1-4-1) 12%4-HH1OB(2F,3F)-O2 (1-4-1) 10% 5-H1OB(2F,3F)-O2 (1-2-1) 11%3-H1OCro(7F,8F)-5 (4-2-1-2)  5% V-HH-5 (3-1-1) 20% V2-HH-3 (3-1-1) 13%3-HVH-5 (—)  6% 3-HB-O2 (3-2-1) 13% NI = 82.1° C.; Δn = 0.075; η = 18.5mPa · s; Δε = −3.4; τ = 12.0 ms.

Example 1

3-H1OB(2F,3F)-O2 (1-2-1) 6% 3-HH2B(2F,3F)-O2 (1-3-1) 4%3-HH1OB(2F,3F)-O2 (1-4-1) 8% V2-HH-2V (2-1) 4% 1V2-HH-V (2-1) 4%1V2-HH-2V1 (2-1) 4% V-HH-3 (3-1-1) 28%  V-HH-5 (3-1-1) 7% 3-HHEH-3(3-4-1) 3% 5-B(F)BB-3 (3-7-1) 4% 5-HBBH-3 (3-11-1) 3% 3-Dh1OB(2F,3F)-O2(4-1-3-1) 4% 5-HDh1OB(2F,3F)-O2 (4-1-6-1) 3% 3-dhBB(2F,3F)-O2 (4-1-7-1)3% 3-H2Cro(7F,8F)-5 (4-2-1-1) 3% 2O-Cro(7F,8F)2H-3 (4-2-2-1) 3%2O-Cro(7F,8F)HH-5 (4-2-4-1) 3% 3-Cro(7F,8F)2HH-5 (4-2-4-2) 3% 1O1-HBBH-5(—) 3% NI = 87.0.0° C.; Tc ≦ −20° C.; Δn = 0.086; η = 17.2 mPa · s; Δε =−2.7; Vth = 2.37 V; τ = 9.9 ms; VHR-1 = 99.2%; VHR-2 = 98.2%; VHR-3 =98.0%.

Example 2

3-H2B(2F,3F)-O2 (1-1-1) 13% 5-H2B(2F, 3F)-O2 (1-1-1) 13%3-HH1OB(2F,3F)-O2 (1-4-1) 10% 3-HBB(2F, 3F)-O2 (1-5-1) 14%5-HBB(2F,3F)-O2 (1-5-1) 10% V-HH-V (2-1) 10% 1V-HH-V (2-1)  7% 1V-HH-V1(2-1)  5% V-HH-2V (2-1) 18% NI = 72.3° C.; Tc ≦ −20° C.; Δn = 0.095; η =15.4 mPa · s; Δε = −3.2; Vth = 2.09 V; τ = 9.5 ms; VHR-1 = 99.0%; VHR-2= 98.0%; VHR-3 = 98.1%.

Example 3

3-H2B(2F,3F)-O2 (1-1-1) 10%  3-H1OB(2F,3F)-O2 (1-2-1) 5%3-H1OB(2F,3F)-O4 (1-2-1) 5% 3-HH1OB(2F,3F)-O2 (1-4-1) 5%5-HH1OB(2F,3F)-O2 (1-4-1) 5% 3-HBB(2F,3F)-O2 (1-5-1) 10% 5-HBB(2F,3F)-O2 (1-5-1) 5% V-HH-V (2-1) 7% 1V-HH-V (2-1) 5% 1V-HH-V1(2-1) 5% V-HH-2V (2-1) 14%  1V2-HH-2V (2-1) 4% V2-BB-1 (3-3-1) 4%3-HBB-2 (3-6-1) 4% 5-HBB-2 (3-6-1) 4% 5-B(F)BB-2 (3-7-1) 4%3-HH1OB(2F,3F,6Me)-O2 (—) 4% NI = 81.4° C.; Tc ≦ −20° C.; Δn = 0.110; η= 16.3 mPa · s; Δε = −2.6; τ = 9.7 ms; VHR-1 = 99.1%; VHR-2 = 98.1%;VHR-3 = 98.1%.

Example 4

3-HBB(2F,3F)-O2 (1-5-1) 13%  V-HH-V (2-1) 8% 1V2-HH-V1 (2-1) 3% V-HH-3(3-1-1) 28%  7-HB-1 (3-2-1) 3% 3-HHB-1 (3-5-1) 4% 3-HHB-O1 (3-5-1) 4%V2-BB(2F)B-1 (3) 6% 3-HB(F)HH-5 (3-10-1) 4% 5-HBB(F)B-2 (3-13-1) 3%5-DhB(2F,3F)-O2 (4-1-1-1) 5% 3-Dh2B(2F,3F)-O2 (4-1-2-1) 5%5-DhHB(2F,3F)-O2 (4-1-4-1) 4% 3-H2Cro(7F,8F)-5 (4-2-1-1) 3%3-H1OCro(7F,8F)-5 (4-2-1-2) 4% 3-HHCro(7F,8F)-5 (4-2-3-1) 3% NI = 84.4°C.; Tc ≦ −20° C.; Δn = 0.099; η = 17.3 mPa · s; Δε = −2.3; τ = 9.9 ms;VHR-1 = 99.2%; VHR-2 = 98.1%; VHR-3 = 98.1%.

Example 5

3-H2B(2F,3F)-O2 (1-1-1) 12%  3-H1OB(2F,3F)-O2 (1-2-1) 8%5-H1OB(2F,3F)-O2 (1-2-1) 8% 3-HH1OB(2F,3F)-O2 (1-4-1) 4% 1V-HH-2V (2-1)6% 1V2-HH-2V (2-1) 6% 2-HH-3 (3-1-1) 20%  1V2-BB-1 (3-3-1) 5% 1V-HBB-2(3-6-1) 4% 2-BB(F)B-3 (3-8-1) 4% 3-HHEBH-5 (3-9-1) 3% 5-HB(F)BH-3(3-12-1) 3% 3-HDhB(2F,3F)-O2 (4-1-5-1) 8% 3-HH2Cro(7F,8F)-5 (4-2-3-2) 3%3-HBCro(7F,8F)-5 (4-2-3-4) 3% 3-BBCro(7F,8F)-5 (4-2-3-5) 3% NI = 72.9°C.; Tc ≦ −20° C.; Δn = 0.099; Δε = −2.6; τ = 11.0 ms; VHR-1 = 99.2%;VHR-2 = 98.2%; VHR-3 = 98.1%.

Example 6

3-HHB(2F,3Cl)-O2 (1) 3% 5-HHB(2F,3Cl)-O2 (1) 2% 3-H2B(2F,3F)-O2 (1-1-1)12%  5-H2B(2F,3F)-O2 (1-1-1) 10%  2-HBB(2F,3F)-O2 (1-5-1) 5%3-HBB(2F,3F)-O2 (1-5-1) 18%  V-HH-V (2-1) 10%  1V-HH-V (2-1) 3% 1V-HH-V1(2-1) 3% 1V-HH-2V (2-1) 6% 3-HH-VFF (3-1) 4% 2-HH-3 (3-1-1) 5% 3-HH-O1(3-1-1) 4% VFF-HHB-1 (3-5) 3% 3-HHB-3 (3-5-1) 3% V2-HHB-1 (3-5-1) 5%3-HHB(2F,3F)-O2 (—) 4% NI = 82.7° C.; Tc ≦ −20° C.; Δn = 0.098; η = 17.0mPa · s; Δε = −2.6; τ = 9.8 ms; VHR-1 = 99.1%; VHR-2 = 98.0%; VHR-3 =98.1%.

Example 7

3-HH1OB(2F,3F)-O2 (1-4-1) 7% 5-HH1OB(2F,3F)-O2 (1-4-1) 7%3-HBB(2F,3F)-O2 (1-5-1) 12%  5-HBB(2F,3F)-O2 (1-5-1) 6% V-HH-V (2-1)12%  1V-HH-V (2-1) 4% 3-HH-4 (3-1-1) 5% 3-HH-5 (3-1-1) 5% 1V-HH-3(3-1-1) 10%  3-HB-O2 (3-2-1) 3% 5-BB-1 (3-3-1) 3% V-HHB-1 (3-5-1) 4%V2-BB(F)B-1 (3-8-1) 3% 3-HH1OCro(7F,8F)-5 (4-2-3-3) 5% 3-HB(2F,3F)-O2(—) 5% V-HB(2F,3F)-O2 (—) 5% V-HB(2F,3F)-O4 (—) 4% NI = 80.1° C.; Tc ≦−20° C.; Δn = 0.097; η = 16.3 mPa · s; Δε = −3.0; τ = 9.7 ms; VHR-1 =99.2%; VHR-2 = 98.1%; VHR-3 = 98.2%.

The compositions in Examples 1 to 7 had a shorter response time thanthat of Comparative example 1 to 3. Thus, the liquid crystal compositionof the invention was so much superior in characteristics to thatdescribed in the patent document No. 1 to 3.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

APPLICABILITY TO THE INDUSTRY

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large dielectric anisotropy,a large specific resistance, a high stability to ultraviolet light and ahigh stability to heat, or that is suitably balanced regarding at leasttwo characteristics. Since a liquid crystal display device containingthe above composition provides an AM device having a short responsetime, a large voltage holding ratio, a large contrast ratio, a longservice life and so forth, it can be used for a liquid crystalprojector, a liquid crystal television and so forth.

1. A liquid crystal composition that has a negative dielectric anisotropy and includes two components, wherein a first component is at least one compound selected from the group of compounds represented by formula (1), and a second component is at least one compound selected from the group of compounds represented by formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; R³ and R⁴ are each independently alkenyl having 2 to 12 carbons; ring A is independently 1,4-cyclohexylene or 1,4-phenylene; Z¹ is independently a single bond, ethylene, methyleneoxy or carbonyloxy; X¹ and X² are each independently fluorine or chlorine; m is 1, 2 or 3; Z⁴ is ethylene, methyleneoxy or carbonyloxy when m is 1 and ring A is 1,4-cyclohexylene; Z⁴ is independently ethylene, methyleneoxy or carbonyloxy when m is 2, two rings A are both 1,4-cyclohexylene.
 2. The liquid crystal composition according to claim 1, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-1) to (1-5):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.
 3. The liquid crystal composition according to claim 2, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-1).
 4. The liquid crystal composition according to claim 2, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-5):
 5. The liquid crystal composition according to claim 2, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-1) and formula (1-5):
 6. The liquid crystal composition according to claim 1, wherein the ratio of the first component is in the range of approximately 5% to approximately 70% by weight, the ratio of the second component is in the range of approximately 5% to approximately 50% by weight, based on the total weight of the liquid crystal composition.
 7. The liquid crystal composition according to claim 1, further including at least one compound selected from the group of compounds represented by formula (3) as a third component:

wherein R⁵ is independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring B and ring C are each independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, or 2,5-difluoro-1,4-phenylene; Z² is independently a single bond, ethylene or carbonyloxy; j is 1, 2 or
 3. 8. The liquid crystal composition according to claim 7, wherein the third component is at least one compound selected from the group of compounds represented by formula (3-1) to formula (3-13):

wherein R⁵ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.
 9. The liquid crystal composition according to claim 8, wherein the third component is at least one compound selected from the group of compounds represented by formula (3-1).
 10. The liquid crystal composition according to claim 8, wherein the third component is at least one compound selected from the group of compounds represented by formula (3-1) and (3-5).
 11. The liquid crystal composition according to claim 7, wherein the ratio of the third component is in the range of approximately 10% to approximately 70% by weight based on the total weight of the liquid crystal composition.
 12. The liquid crystal composition according to claim 1, wherein the fourth component is at least one compound selected from the group of compounds represented by formula (4-1) to formula (4-2):

wherein, R² and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring D is independently tetrahydropyran-2,5-diyl, 1,4-cyclohexylene or 1,4-phenylene, and at least one ring D is tetrahydropyran-2,5-diyl; ring E and F are each independently 1,4-cyclohexylene or 1,4-phenylene; Z² and Z³ are each independently a single bond, ethylene, methyleneoxy, or carbonyloxy; k is 1, 2 or 3; p and q are each independently 0, 1, 2 or 3, and the sum of p and q is 3 or less.
 13. The liquid crystal composition according to claim 7, wherein the fourth component is at least one compound selected from the group of compounds represented by formula (4-1) to formula (4-2):

wherein, R² and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring D is independently tetrahydropyran-2,5-diyl, 1,4-cyclohexylene or 1,4-phenylene, and at least one ring D is tetrahydropyran-2,5-diyl; ring E and F are each independently 1,4-cyclohexylene or 1,4-phenylene; Z² and Z³ are each independently a single bond, ethylene, methyleneoxy, or carbonyloxy; k is 1, 2 or 3; p and q are each independently 0, 1, 2 or 3, and the sum of p and q is 3 or less.
 14. The liquid crystal composition according to claim 12, wherein the fourth component is at least one compound selected from the group of compounds represented by formula (4-1-1) to formula (4-1-7), and the formula (4-2-1) to (4-2-4):

wherein, R¹ and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring E¹, E², F¹ and F² are each independently 1,4-cyclohexylene or 1,4-phenylene; and Z¹ and Z³ are each independently a single bond, ethylene, methyleneoxy, or carbonyloxy.
 15. The liquid crystal composition according to claim 13, wherein the fourth component is at least one compound selected from the group of compounds represented by formula (4-1-1) to formula (4-1-7), and the formula (4-2-1) to (4-2-4):

wherein, R² and R² are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring E¹, E², F¹ and F² are each independently 1,4-cyclohexylene or 1,4-phenylene; and Z² and Z³ are each independently a single bond, ethylene, methyleneoxy, or carbonyloxy.
 16. The liquid crystal composition according to claim 12, wherein the ratio of the fourth component is in the range of approximately 5% to approximately 40% by weight, based on the total weight of the liquid crystal composition.
 17. The liquid crystal composition according to claim 13, wherein the ratio of the fourth component is in the range of approximately 5% to approximately 40% by weight, based on the total weight of the liquid crystal composition.
 18. The liquid crystal composition according to claim 1, wherein the maximum temperature of the nematic phase is approximately 70° C. or higher, the optical anisotropy (25° C.) at a wavelength of 589 nm is approximately 0.08 or more, and the dielectric anisotropy (25° C.) at a frequency of 1 kHz is approximately −2 or less.
 19. A liquid crystal display device containing the liquid crystal composition according to claim
 1. 20. The liquid crystal display device according to claim 19, wherein an operating mode of the liquid crystal display device is a VA mode, an IPS mode or a PSA mode, and a driving mode of the liquid crystal display device is an active matrix mode. 